The present application claims priority under 35 U.S.C. xc2xa7119 of German Patent Application No. 299 10 850.3, filed on Jun. 25, 1999, the disclosure of which is expressly incorporated by reference herein in its entirety.
1. Field of the Invention
The invention relates to a vacuum conveyor which is suitable for guiding a
2. Background of the Invention
Conveyors of the above-mentioned type, e.g., as disclosed in DE 26 36 887, have proven successful in operation. However, in many applications a disturbing factor is that with the known conveyor the connection for the vacuum pipe is arranged at one of the side walls of the suction box. Such an arrangement of the vacuum connection seems suitable because only the two side walls of the suction box are outwardly free, i.e., are accessible directly from outside. In most cases the two pulleys over which the endless conveyor belt runs, and the suction box located in between, fill the interior space of the endless conveyor belt almost completely.
Overall, there are several demands that should be fulfilled by a vacuum conveyor. For example, the vacuum conveyor should be suitable for as many different installation situations as possible and also be capable of being used in particularly restricted spaces. More precisely, the maximum construction width, including the vacuum connection, should, if possible, be only a little larger than the width of the web to be carried, especially the width of a threading tail, e.g., between approximately 0.1 and 0.4 m.
Moreover, the tendency for dirt particles or similar materials to collect during operation at the conveyor belt and/or in the suction box should be reduced.
The present invention provides a vacuum conveyor which meets as many of the above-stated demands as possible and which includes an air flow path, from the suction box to a vacuum source, that runs through a return run of the conveyor belt.
By drawing off the air by suction, i.e., for the purpose of generating a vacuum in the suction box, through the return run of the conveyor belt, the above-mentioned drawbacks can be resolved. Further, while the design work required for the vacuum connection is slightly greater than in previous vacuum conveyors, the instant invention achieves a considerable advantage in that the width of the vacuum connection requires no additional construction space over the width of the conveyor itself In this way, the conveyor can be more universally applicable than in the past, and even if only relatively little space is available, it is also more easily accessible than before.
A further advantage of the solution in accordance with the invention is that the air flow through the suction box and through the vacuum connection does not include any deflection to the side. This makes it possible for the air flow to remove any existing dirt particles from the conveyor more reliably than in the past. In particular, the tendency for dirt to collect inside the suction box is reduced, and the pores of the conveyor belt are kept free from dust deposits better than before. Thus, a continuous self-cleaning effect can be achieved.
In the area of the return run of the conveyor belt, a relatively large flow cross-section can be provided between the suction box and the external vacuum piping (e.g., in a so-called xe2x80x9csuction nozzlexe2x80x9d). Therefore, in accordance with the invention, it is possible to generate a higher vacuum than before in the suction box, without consuming more power.
A further characteristic feature of the vacuum conveyor of the invention is the supporting device which connects the suction box with the suction nozzle. In particular, it is noted that, according to the invention, the supporting device grips around the edges of the return run of the belt.
Various types of sealing elements may be used at an exhaust opening of the suction box and/or around the air flow path going through the supporting device.
While those sealing elements might be helpful to avoid an undesired inflow of secondary air into the suction nozzle, sliding friction could result from the sliding motion of the belt over the sealings. In order to resolve this problem, a small gap may be formed between the suction box and an inner side of the belt""s return run. In this way, the gap can be free of any sealing elements. Moreover, two roll-type sealing elements which extend across the belt travel direction can be arranged between the supporting device and the belt""s return run.
Further advantageous features of the invention include that the suction nozzle, without the suction pipe or together with the suction pipe, could perform a double function. In particular, it can be used both to exhaust the air and to carry the conveyor, i.e., to fasten the conveyor to a machine frame, rack or similar structure.
The present invention is directed to a vacuum conveyor for guiding at least a portion of a running web into a machine for one of producing, finishing, or processing the web. The vacuum conveyor includes two rotatably mounted pulleys, an air-previous endless conveyor belt tensioned over the two pulleys to form a loop including a conveying run and a return run, and a vacuum source. A suction box is located in the loop of the conveyor belt and is coupled to the vacuum source through an air flow path. In this way, a vacuum propagates through the conveying run to suction the web to be guided onto the conveyor belt. The air flow path is arranged to through the return run of the conveyor belt.
According to a feature of the instant invention, the at least a portion of the running web comprises a threading tail. Further, the web includes one of a paper and board web, and at least one of the two pulleys is a driven pulley.
Further, the suction box can include at least one exhaust opening which is open toward the return run, and the vacuum conveyor can further include a suction nozzle located outside of the loop of the conveyor belt which is open to the exhaust opening, and a vacuum pipe can be coupled to the suction nozzle. Further, a supporting device can be arranged to rigidly couple the suction nozzle and the suction box to each other. The supporting device may include a portion arranged to extend around edges of the return run.
Further, sliding elements may be arranged at at least one of the exhaust opening, the suction nozzle and the supporting device, so that the conveyor belt is arranged to slide over the sliding elements. The supporting device can include a plate arranged substantially parallel to the return run and can have an exhaust opening which at least approximately coincides with the exhaust opening of the suction box. Sealing elements can be arranged at the supporting device between the plate and the return run. A gap can be formed between the suction box and an inner side of the return run, such that the gap is free of any sealing elements. The sealing elements arranged at the supporting device may include two rotatable sealing elements, each being formed as a cylindrical roll. The sealing elements may be arranged to extend cross-wise to the return run, and, relative to a travel direction of the return run, one of the sealing elements can be arranged in front of the exhaust opening of the supporting device and other of the sealing elements can be arranged after the exhaust opening.
The rotatable sealing elements may be arranged to allow contact between the sealing elements and an outside of the return run and to avoid contact between the sealing elements and the plate. The two rotating sealing elements can be the only sealing device arranged in a vicinity of the air-flow path from the suction box to the suction nozzle.
In accordance with another feature of the invention, the supporting device may include a support for a drive adapted to drive one of the two pulleys.
Further, the suction nozzle may include a portion of an assembly entirely supporting the vacuum conveyor. A part of the vacuum pipe, which connects the suction nozzle to the vacuum source, may be an integral part of the assembly supporting the vacuum conveyor.
The present invention is directed to a vacuum conveyor for transporting at least a portion of a material web in a web travel direction. The vacuum conveyor includes two pulleys, a suction box positioned between the two pulleys, and an endless conveyor belt arranged around the two pulleys to form a loop. The suction box is positioned within the loop and the loop includes a conveyor run adapted to contact and guide the material web and a return run moving in a direction opposite the conveyor run. The suction box includes a suction opening positioned adjacent the conveyor run to suction the material web onto the conveyor belt and an exhaust opening positioned adjacent the return run. A vacuum source is coupled to the exhaust opening through the return run.
According to a feature of the invention, a vacuum pipe can be coupled between the vacuum source and the exhaust opening, and a supporting device can be arranged to couple the suction box to the vacuum pipe. At least one rotatable sealing element may be provided, and the supporting device includes a rotatable sealing element holding portion to rotatably couple the at least one sealing element to the supporting device. The at least one rotatable sealing element can be positioned in contact with the return run. The vacuum conveyor can be adapted to convey a threading strip of the material web.
In accordance with another feature of the instant invention, a drive motor may be coupled to at least one of the two pulleys.
The present invention includes a process for conveying at least a portion of a material web with an apparatus that includes two rotatably mounted pulleys, an air-previous endless conveyor belt tensioned over the two pulleys to form a loop including a conveying run and a return run, a vacuum source, and a suction box located in the loop of the conveyor belt. The process includes creating a suction air flow from the vacuum source to the suction box through the return run of the conveyor belt, suctioning the at least a portion of the material web onto a conveying run of an endless conveyor with a suction box having a suction opening positioned adjacent at least a portion of the conveying run, and moving the endless conveyor to transport the at least a portion of the material web.
In accordance with a feature of the invention, the process can further include blowing the at least a portion of the material web away from the conveying run at an end of the conveying run.
According to another feature of the instant invention, the at least a portion of the material web can include a threading strip.
In accordance with yet another feature of the present invention, at least one of the two pulleys can be driven by a motor, thereby moving the conveyor belt.
Other exemplary embodiments and advantages of the present invention may be ascertained by reviewing the present disclosure and the accompanying drawing.